1. Field of the Invention
The subject invention relates to speed or "cruise" control systems for automobiles. More specifically, it relates to an electronically controlled speed control system utilizing methods of control in a microcomputer circuit.
2. Description of the Related Art
U.S. Pat. No. 3,722,614 issued on Mar. 27, 1973 to Sakakibara et al., "Method And Apparatus For Causing Constant Traveling Speed Of Automotive Vehicles," discloses an early version of electronic speed control utilizing servo motors and sensing the traveling speed of a vehicle with a pulse width.
U.S. Pat. No. 4,066,874 issued on Jan. 3, 1978, to Mark L. Shaw, "Digital Speed Control System," discloses a logic circuit for use in a velocity control system. This patent describes a discrete digital system for controlling speed and acceleration and digital means to calculate acceleration.
Also issued on Jan. 3, 1978 is U.S. Pat. No. 4,066,876 to Mark L. Shaw et al., "Digital Speed Control System," which also discloses a discrete digital logic velocity control system.
U.S. Pat. No. 4,250,854 issued on Feb. 17, 1981 to Matsui et al., "Speed Control System For Automotive Vehicles," discloses a speed difference calculation circuit which is provided to calculate a first time difference between a predetermined period of time corresponding with the desired vehicle speed and the actual period of time corresponding with the actual vehicle speed, along with an acceleration calculation circuit. A correlation signal is obtained dependent on each value of two calculated time differences to control the quantity of fuel supplied into the engine so as to maintain the speed of the vehicle as the desired value.
U.S. Pat. No. 4,335,799 issued on June 22, 1982 to Neal G. Shields, "Speed Governor With Below Dashboard Servomotor," deals with the interior mounting of a vacuum servo so that installation is less sensitive to vehicle design.
U.S. Pat. No. 4,340,824 issued on July 20, 1982 to Mark L. Shaw, "Auxiliary Steering Wheel Command System," deals with a multiplexing data switch selection through the steering column, including those used for speed control.
U.S. Pat. No. 4,345,663 issued on Aug. 24, 1982 to Neal G. Shields, "Speed Governor With Dual Safety System," deals with the safety dump valve being independent of a control circuit or a control break switch.
U.S. Pat. No. 4,352,403 issued on Oct. 5, 1982 to Charles F. Burney, "Vehicle Speed Control System," discloses a system which decreases the amount of acceleration given the vehicle as the desired speed is approached in order to assure a smooth, positive transition to desired speed. This is done with discrete electronic componentry.
U.S. Pat. No. 4,394,739 issued on July 19, 1983 to Suzuki et al., "Automatic Speed Control For An Automotive Vehicle," discloses a circuit and method to deal with a stuck resume button in an analog circuit speed control system.
U.S. Pat. No. 4,431,077 issued on Feb. 14, 1984, to Charles F. Burney, "Vehicle Speed Control System," is related to U.S. Pat. No. 4,352,403 previously described. It discloses a throttle feedback/speed error control system with a potentiometer set for the desired speed. It involves the use of analog and discrete digital components.
U.S. Pat. No. 4,451,888 issued on May 29, 1984 to Kuno et al., "Speed Control Method And Apparatus For Automotive Vehicles," discloses an electronic circuit and method for vehicle speed control which appears to utilize discrete electronic componentry.
U.S. Pat. No. 4,451,890 issued on May 29, 1984, to Suzuki et al., "Automatic Speed Control System For An Automotive Vehicle," provides a means of responding to a stuck resume button in an analog circuit for speed control and is related to U.S. Pat. No. 4,394,739 which is described above.
U.S. Pat. No. 4,463,822 issued on Aug. 7, 1984, to Tanigawa et al., "Cruise Control System For Automotive Vehicle," discloses an overdrive controller in combination with a cruise control system which will automatically shift the transmission of the vehicle in and out of overdrive in response and in conjunction with the controlling of the speed by the electronic cruise control system.
U.S. Pat. No. 4,467,428 issued on Aug. 21, 1984, to Caldwell, "Automatic Speed Control Systems," discloses a speed control system mainly for heavy duty vehicles which operate mostly on major highways. The disclosure describes a system which anticipates an uphill portion of the highway immediately following a downhill portion of the highway and anticipates the need for an increase throttle action by the heavy equipment vehicle while climbing the hill. Therefore, the system is designed to prevent the loss of momentum obtained by the vehicle as it is descending a hill and use the same momentum in ascending the anticipated following uphill climb.
U.S. Pat. No. 4,470,478 issued on Sept. 11, 1984, to Hayashi et al., "Vehicle Speed Control Apparatus With Set Increase," discloses a vehicle speed control system which is capable of preventing a setting operation from being carried out when an increase switch, for increasing the stored running speed, malfunctions.
U.S. Pat. No. 4,472,777 issued on Sept. 18, 1984, to Youngblood, "Engine Control Apparatus For Vehicle Speed," discloses a system which utilizes various sensors throughout the engine and vehicle and interfaces the signals from these sensors logically to a controller to limit the speed on the engine as a function of the condition of the sensors to, therefore, provide a safeguard against uncontrolled vehicle accelerations.
U.S. Pat. No. 4,479,184 issued on Oct. 23, 1984 to Nakano, "Device For Maintaining a Constant Vehicle Speed," discloses a cruise control system which utilizes a proportional speed error and two actuators to control the speed of the engine and, therefore, the speed of the vehicle. This is accomplished by controlling the main actuator which controls the throttle angle and, in addition, controlling the speed fluctuation by controlling an additional actuator which blends more or less error in an auxiliary passage around the throttle blade to alter the air fuel ratio in the engine and thereby control the speed fluctuations and fine tune the control of the vehicle speed.
U.S. Pat. No. 4,478,184 issued on Oct. 23, 1984 to Shinoda et al., "Speed Control System And Method For Automotive Vehicles," where a system is disclosed to adjust the absolute value of a differential speed signal and adjust the value of corresponding control signals to produce a correction to the vehicle speed based on the absolute value of the differential signal.
U.S. Pat. No. 4,484,279 issued on Nov. 20, 1984 to Muto, "Vehicle Speed Control Method," discloses a system which allows the driver, upon initiation of the speed control device, to select the initial speed that the vehicle is traveling upon the initial actuation of the set switch. The system provides for the selection of this initial speed regardless of the length of the actuation period of the set switch upon this initial engagement of the electronic cruise control.
U.S. Pat. No. 4,488,527 issued on Dec. 18, 1984, to Pfalzgraf et al., "Device For Controlling The Speed Of Travel Of An Automotive Vehicle" provides an alarm circuit and an interaction with a controller which generates an alarm if an error is detected such as a defect in the pedal contact or of the setting member contact and sends a signal to the controller which will limit the operation of the entire system to prevent dangerous conditions.
U.S. Pat. No. 4,501,284 issued on Feb. 26, 1985 to Kuno et al., "Speed Control Method And System For Automotive Vehicles," discloses a speed control system to precisely control the fuel supply into the engine over a wide range of vehicle speed by maintaining the resolution of the calculated value independent of the speed of the vehicle.
U.S. Pat. No. 4,516,652 issued on May 14, 1985 to Tanigawa et al., "Apparatus For Controlling The Speed Of An Automobile," discloses an apparatus for controlling the speed and interacting with the switch of the transmission gear in or out of an overdrive condition.
U.S. Pat. No. 4,522,280 issued on June 11, 1985, to Blaney, "Automatic Disengagement Device For Automotive Cruise Control System," describes a system which responds to the actuation or malfunction of a brake switch to disconnect the automotive cruise control circuitry; it also responds to the condition of a power lead connected to the throttle actuator to disconnect the cruise control in case of a malfunction and it also responds to a comparison of a predetermined threshold operating speed as compared to a peak operating speed which will result under certain conditions in the automatic disconnection of the electronic cruise control system.
U.S. Pat. No. 4,549,266 issued on Oct. 22, 1985, to Schneider et al., "Vehicle Speed Control," describes an automotive speed control system which uses logic activated switches on both sides of electrical solenoids which control vent and vacuum valves to reduce the effects of shorting a switch in a system utilizing only one switch in series with the solenoids.
U.S. Pat. No. 4,597,465 issued on July 1, 1986, to Burney, "Cruise Control System And Method With Overspeed Sensor," discloses a system to disengage the cruise control if an overspeed sensor which monitors the engine speed senses a sudden increase in the engine speed, such as may occur with the depression of the clutch in a vehicle having a manual transmission.
U.S. Pat. No. 4,606,425 issued on Aug. 19, 1986, to Hayashi et al., "Vehicle Speed Control Apparatus," is closely related to U.S. Pat. No. 4,470,478 which has already been described above.
U.S. Pat. No. 4,608,954 issued on Sept. 2, 1986, to Gray, "Input Circuit for An Electronic Vehicle Speed Control Unit," discloses an electronic control circuit to control the supply of vacuum which is resistant to spurious noise signals generated from such sources as the vehicle ignition system.
Of interest is SAE Paper No. 830662 by Peter G. Blaney entitled "Improvement To Cruise Controls Utilizing Microprocessor Technology" which was presented at the International Congress and Exhibition in Detroit, Mich., Feb. 28-Mar. 4, 1983. This paper is hereby expressly incorporated by reference.
Also of interest is a paper entitled "New LSI Circuits That Optimize Cruise Control Systems" by Mark L. Shaw, presented at the INTERNEPCON 1978 conference.